S&P 500 touches record high, equals longest-ever bull run

And even without a near-20% drop, there have been periods in just the last three years for US stock market investors that were less than exuberant.

The Dow Jones Industrial Average fell 88.69 points, or 0.34 per cent, to 25,733.60.

The S&P 500 energy index .SPNY rose 0.9 percent and the S&P 500 materials index .SPLRCM gained 0.6 percent, in tandem with higher prices for oil and metals. Market watchers point to a variety of potential threats to the bull market, including a global slowdown prompted by the myriad trade conflicts initiated by Trump.

The S&P 500 finished the day down less than 0.1 percent at 2,861.82.

At the close of trading on Wall Street, the S&P 500 was off its high for the day, up 0.18% to 2862.41, the Dow Jones Industrial Average rose 0.25% to 25,822.02 and the tech-heavy Nasdaq Composite was up 0.45% at 7855.01.

"There was quite a lot of news that was negative for Trump yesterday that introduced uncertainty into the market", said Robert Phipps, director at Per Stirling Capital Management in Austin, Texas. That represents the bottom of the 1987 bear market that began on 8/25/1987 and culminated in the low on 12/4/1987 with the S&P 500 Index down 33.51%.

CENTRAL BANKS: Aside from that milestone, investors will have a heap of information from central banks, staring Wednesday with the release of the minutes to the U.S. Federal Reserve's last rate-setting meeting.